7. Organic Chemistry Flashcards
1
Q
What is a hydrocarbon?
A
A fuel; a molecule that consists of hydrogen and carbon
2
Q
What is crude oil?
A
A fuel made from remains of marine plants and animals to form sedimentary rock. When pressure and heat was added the rock was broken down to form crude oil and natural gas
3
Q
What are many of the compounds in crude oil?
A
Hydrocarbons - mostly alkanes
4
Q
What is an alkane?
A
Contains a single chains of carbon atoms with hydrogen atoms bonded along the side
5
Q
What is the formula for alkanes?
A
CnH2n+2
6
Q
What is the simplest alkane?
A
Methane
7
Q
What are the four simplest alkanes?
A
Methane, ethane, propane and butane
8
Q
What is a molecular formula?
A
Gives number of atoms of each element in a molecule
9
Q
What is a structural formula?
A
Shows the atoms molecule by molecule
10
Q
What is the displayed formula?
A
Shows how atoms are arranged and the bonds between them
11
Q
What happens as the number of carbons in a molecule increases?
A
Boiling point increases because more energy is needed to break the intermolecular forces
12
Q
Gases in fractional distillation which have the lowest boiling point also are…
A
The most volatile and flammable
13
Q
What is viscosity?
A
The resistance of flow that a liquid has
14
Q
What happens in fractional distillation as molecule size decreases in terms of colour?
A
Becomes lighter: black, yellow, transparent
15
Q
Why are hydrocarbons cracked?
A
Long chains are not useful
16
Q
What types of cracking are there?
A
Thermal and catalytic cracking
17
Q
Why are fractions with large hydrocarbon molecules more viscous?
A
Longer chains are easily entangled. The amount of intermolecular force also affects viscosity
18
Q
How is thermal cracking carried out?
A
Long hydrocarbon chains are vaporised, and placed under high pressure and temperatures (~750c) and thermal decomposition takes place - chains are split apart
19
Q
How is catalytic cracking carried out?
A
Long hydrocarbon chains are vaporised and passed over a hot catalyst - heat to a high temperature (~500c). Chains cracked as thermal decomposition takes place
20
Q
What is a disadvantage of thermal cracking?
A
There is not a lot of control over what products are formed
21
Q
What is an advantage of catalytic cracking?
A
Longer chains are split to smaller chains - about 8-10 carbons in length
22
Q
What does cracking hydrocarbons produce?
A
A mixture of alkanes and alkenes
23
Q
Why are porcelain chips used in catalytic cracking in the lab?
A
As a catalyst - where thermal decomposition takes place
24
Q
What are alkenes used to produce?
A
Polymers (plastics)
25
What is the general formula for alkenes?
CnH2n
26
What bond does an alkene contain?
A double carbon-carbon bond
27
What is the simplest alkene?
Ethene - C2H4
28
What are the four simplest alkenes?
Ethene, propene, butene, pentene
29
An example of a saturated compound?
Alkanes
30
An example of an unsaturated compound?
Alkenes
31
What is a saturated compound?
Contains only single covalent bonds
32
What is an unsaturated compound?
Contains at least one double covalent bond
33
What is the test alkenes?
Will turn bromine water from orange to clear
34
Why do alkenes react with bromine water but alkanes don't?
Alkenes have a double bond which can open up to react with bromine
35
What is a functional group?
The part of a molecule responsible for reactions
36
Example of a functional group?
The double bond in alkenes
37
What is a homologous series?
A series of compounds that have similar properties and the same general formula
38
How do the successive members of alkenes differ from each other?
As the carbon number increases by one, the number of hydrogens increases different numbers
39
What type of combustion do alkenes tend to undergo?
Incomplete, but some may be complete
40
How do alkenes burn compared to alkanes?
With a smokier, yellow flame
41
Which releases more energy per mole during combustion: alkenes or alkanes?
Alkanes
42
Why is it better to use octane in a car engine and not octene?
* octene undergoes incomplete combustion and so is very smoky and produces more pollution
* octane releases mor energy per mole so is more efficient
43
How do we know that halogens and alkenes undergo addition reactions?
Bromine water turning colourless
44
Why do addition reactions of alkenes occur?
* the double carbon bond in alkenes make them more reactive than alkanes (its electron dense)
* the double bond can open and react with other the carbons to add to the molecule
45
What does ethene + bromine give?
Dibromoethane
46
What does propene + bromine give?
Dibromopropane
47
What does ethene + chlorine give?
Dichloroethane
48
What does propene + iodine give?
Diiodopropane
49
How can alkenes become saturated?
By adding hydrogen
50
What conditions are required for the hydrogenation of alkenes?
* 60*C
| * nickel catalyst
51
What does ethene + hydrogen give?
Ethane
52
Why would an alkene needed to be turned into an alkane?
To straighten the molecules - the closer they can get to each other means that they have stronger intermolecular forces
53
Why bother turning an alkene to an alkanae? i.e. from unsaturated to saturated
To increase melting point
54
Practical application of hydrogenation of alkenes?
To make margarine - enough hydrogen should be added to make it spreadable straight from the fridge - but not too little to make it a liquid
55
What is the process of hydrogenation?
* addition of hydrogen across the alkene's double bond
* replaces double carbon bond to a single
* nickel catalyst at 60 degrees
* causes melting point to increase so become solid at room temperature
56
What is the addition reactions of hydrogen to alkenes also known as?
Hydrogenation of alkenes
57
Advantages of addition reactions of hydrogen and alkenes (hydrogenation)?
* more useful as a solid
| * can be used as margarine
58
Disadvantages of addition reactions of hydrogen and alkenes (hydrogenation)?
• saturated fats are not healthy as the molecules pack closely together so bonds are harder to break
59
Why are saturated fats more unhealthy?
Because the molecules are packed closer together - making it harder to break the bonds
60
How can ethanol be made?
From the hydration of ethene
61
What can the addition reactions of water also be known as?
Hydration
62
What is hydration?
The addition of water
63
What conditions are required for hydration?
* concentrated phosphoric acid catalyst
| * high temperature and pressure
64
What does ethene + water give?
Ethanol
65
Is hydration of alkenes reversible?
• yes, ethanol can break back down to steam and water
66
What happens to the unreacted ethene and stream during hydration?
Recycled over the catalyst
67
What can propene + water give?
* propan-1-ol
* propan-2-ol
(they are both propanol)
68
How many molecules are needed in a halogen, hydrogen or water addition reaction?
Only one molecule as there is only one double bond to open up
69
What does each bromine atom bond to during an addition reaction of Br2 and an alkene?
* one bromine molecule bonds to one carbon from the double bond
* the other bromine bonds to the other carbon from the double bond
70
During a hydration reaction, what parts of the alkene do the H2O molecules bond to?
* one hydrogen bonds to one of the carbons from the double bond
* OH bonds to the other carbon
71
Uses alcohols?
* drinks
* perfumes
* solvent
* fuel
* antiseptic
72
What are the ways of producing ethanol industrially?
* hydration of ethene
| * fermentation of glucose
73
How is glucose fermented to produce ethanol?
1. Extract sugar (glucose) from crops
2. Add yeast - enzymes act as catalyst
3. Fermentation - a type of anaerobic respiration
74
What conditions are required for the fermentation to glucose to produce ethanol?
* 30-40*C
* CO2 released
* batch process (stop and starts)
75
What is produced along with ethanol during fermentation of glucose?
Carbon dioxide
76
Advantages of using fermentation of glucose to produce ethanol?
* sugar - renewable resource
* batch process - cheap equipment needed
* more carbon neutral
77
Disadvantages of using fermentation of glucose to produce ethanol?
* very slow
* very impure - needs further processing -> fractional distillation
* batch process means high labour costs
78
How is ethene hydrated to produce ethanol?
1. Extract crude oil from the ground
2. Oil refinery - fractional distillation then cracking to produce ethene
3. Hydration (addition of water/steam)
79
What conditions are required for the hydration of ethene to produce ethanol?
* phosphoric acid catalyst
* high temperature and pressure
* continuous process
80
Advantages of using hydration of ethene to produce ethanol?
* fast reaction
* pure product
* 95% yield - initially 5% but ethene is recycled
* continuous - cheaper man power
81
Disadvantages of using hydration of ethene to produce ethanol?
* high technology equipment needed - expensive initially
* high energy costs for high pressure
* ethene is non-renewable
82
What is the functional group of alcohols?
-OH
83
How many bonds must each type of atom form in an alcohol?
* each carbon must form 4 bonds
* each hydrogen - 1 bond
* each oxygen - 2 bonds
84
Are alcohols hydrocarbons?
No because they contain oxygen as well as carbon and hydrogen
85
What is the general formula of alcohols?
Cn H2n+1 OH
86
What are carboxylic acids?
Homologous series with the functional group COOH
87
What is the functional group of carboxylic acids?
COOH
88
What are the names of the first four carboxylic acids?
* methanoic acid
* ethanoic acid
* propanoic acid
* butanoic acid
89
What is the structural formula for methanoic acid?
HCOOH
90
What is the structural formula for ethanoic acid?
CH3COOH
91
What is the structural formula for propanoic acid?
CH3CH2COOH
92
What is the structural formula for butanoic acid?
CH3CH2CH2COOH
93
What happens when ethanoic acid is dissolved in water?
It becomes acidic, turning universal indicator red
94
What happens when ethanoic acid reacts with a metal carbonate?
It fizzes, showing carbon dioxide is produced (with salt and water)
95
What does carboxylic acid + metal carbonate give?
Salt + water + carbon dioxide
96
What do carboxylic acids produce when they react with alcohols?
An ester bond between the two molecules
97
What are esters?
Chemicals with pleasant smells
98
What are esters used in?
Perfumes and solvents
99
What is formed, as well as an ester bond, when carboxylic acids react with alcohols?
Water
100
Is a catalyst used in the production of ester bonds? If so, what?
Yes. Acid is used as a catalyst - usually sulphuric acid
101
What is formed when ethanoic acid reacts with ethanol?
Ethyl ethanoate and water
102
Is the reaction of carbxylic acids and alcohols reversible?
Yes
103
What is pH the measure of?
The hydrogen ions in a solution
104
What type of acids ionise fully in water?
Strong acids
105
What is the concentration of hydrogen atoms like in solutions of strong acids?
There is a high concentration of hydrogen ions, giving it a low pH
106
Are carboxylic acids strong or weak?
Weak
107
Do carboxylic acids ionise fully when they are dissolved in water?
No, instead only some of their molecules ionise to form hydrogen ions
108
What is a polymer?
A long chain molecule made from small molecules called monomers
109
How can alkenes be used make polymers?
Addition polymerisation
110
What is addition polymerisation?
When monomers with double bonds form a polymer with single bonds
111
What conditions does polymerisation generally need?
* high temperatures and pressures
| * a catalyst
112
Why does the polymerisation of ethene have an atom economy of 100%?
Because there is only one product
113
What are two uses of poly(ethene)?
* plastic bags
| * drinks bottles
114
What are two uses of poly(propene)?
* food packaging
| * furniture
115
What does condensation polymerisation involve?
Monomers with two functional groups
116
What are some examples of condensation polymers?
* nylon
* kevlar
* polyesters
117
What are the simplest condensation polymers made from?
Two different monomers with two of the same functional groups on each monomer
118
What bonds are formed in most condensation reactions?
An ester or amide bond
119
When are ester bonds formed?
When carboxylic acids and alcohols react
120
What are amide bonds formed?
When carboxylic acids and amines (-NH2) react
121
Where do the new bonds form in condensation polymerisation reactions?
Where the functional groups are located
122
What is produced when a dicarboxylic acid and a dialcohol react?
* a polyester (with an ester bond)
| * water
123
What has to react in order to produce a polyester?
A dicarboxylic acid and a dialcohol
124
During what type of reaction is a polyester formed?
Condensation polymerisation
125
What is produced when a dicarboxylic acid and a diamine react?
* a polyamide (with an amide bond)
| * water
126
What has to react in order to produce a polyamide?
A dicarboxylic acid and a diamine
127
During what type of reaction is a polyamide formed?
Condensation polymerisation
128
What is the function group of carboxylic acids, alcohols and amines?
* carboxylic acids - COOH
* alcohols - OH
* amines - NH2
129
What is the basic structure of an amino acids?
An amine group on one side and a carboxylic acid on the other
130
How many amino acids are there?
21
131
What functional groups do amino acids contain?
* carboxyl (-COOH)
| * amine (-NH2)
132
What does an amino acid contain aswell as the carboxyl and amine functional groups?
A side chain (R group) specific to each amino acid
133
What do amino acids react by condensation polymerisation to produce?
Polypeptides
134
What does the amino acid glycine (H2NCH2COOH) polymerise to produce?
* the polypeptide (HNCH2CO)
| * water
135
How can amino acids produce proteins?
When they are combined in the same chain
136
What does DNA stand for?
Deoxyribonucleic acid
137
What does DNA do?
Encodes genetic instructions for development and functioning of organisms and viruses
138
What is the structure of DNA like?
Two polymer chains, made from 4 different monomers (nucleotides), in a double helix
139
What is the difference in how addition and condensation polymers are made?
Addition polymers - many monomers join together to form polymers, double bond opens up, no other substance formed
Condensation polymers - monomers join to make polymer as well as other small molecules, water often given off
140
What is the difference in the type of molecules the monomers are in addition and condensation polymers?
Addition polymers - alkenes
Condensation polymers - molecules with two functional groups
